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Some aspects of the problem of choosing a gas fire extinguishing agent in gas fire extinguishing installations. Automatic gas fire extinguishing, areas of application, characteristics of systems Fire fighting gas

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Non-state educational institution of secondary vocational education International Police Association College of Law

Course work

Fire extinguishing agents used in automatic fire extinguishing installations

Completed by: Gorbushin Ilya Nikolaevich

Course 3 group 4411

Specialty: 280703 Fire safety

Head: Peskichev S.V.

Introduction

1. Classification of fire extinguishing agents

1.1 Water installations

1.2 Powder plants

1.3 Gas installations

1.4 Foam plants

1.5 Aerosol plants

1.6 Combined installation

2. Cases in which the installation of automatic fire extinguishing systems is mandatory

2.1 Advantages and disadvantages automatic fire extinguishing

Conclusion

Bibliographic list

Introduction

Automatic fire extinguishing systems serve to rapid response for signs of fire and fire prevention. They can be compared to a fire brigade permanently on site.

Automatic fire extinguishing systems can be installed in almost any room. The most relevant locations for such systems are large parking lots. closed type, server rooms, production facilities where there is a possibility of fire during the production process, document archives, etc.

1. Classificationautomaticsystemsfirefighting

Fire extinguishing installations - a set of stationary technical means extinguishing a fire by releasing a fire extinguishing agent. Fire extinguishing installations must ensure the localization or elimination of a fire.

Fire extinguishing installations constructive device subdivided into aggregate and modular.

According to the degree of automation - automatic, automated and manual.

By type of fire extinguishing agent - water, foam, gas, powder, aerosol and combined.

According to the method of extinguishing - into volumetric, surface, locally-volumetric and locally-surface.

1. 1 Waterinstallations

Water installations are sprinkler and deluge. Sprinkler installations are designed for local extinguishing of fires in rapidly flammable premises, for example, wooden ones, and deluge installations are designed to extinguish a fire immediately throughout the facility.

In sprinkler extinguishing systems, the sprinkler (sprinkler) is mounted in a pipeline filled with water, special foam (if the room temperature is above 5°C) or air (if the room temperature is below 5°C). In this case, the extinguishing agent is constantly under pressure. There are combined sprinkler systems in which the supply pipeline is filled with water, and the supply and distribution pipes can be filled with air or water, depending on the season. The sprinkler is closed with a thermal lock, which is a special flask designed for depressurization when a certain ambient temperature is reached.

After the sprinkler is depressurized, the pressure in the pipeline decreases, due to which a special valve in the control unit opens. After that, the water rushes to the detector, which detects the operation and gives a command signal to turn on the pump.

Sprinkler fire extinguishing systems are used for local detection and elimination of fires with the activation of fire alarms, special warning systems, smoke protection, evacuation management and provision of information about fire locations. The service life of sprinklers that have not been activated is ten years, and sprinklers that have been activated or damaged must be completely replaced. During the design of the pipeline network, it is divided into sections. Each of these sections can serve one or several rooms at once, and can also have a separate control unit fire fighting system. An automatic pump is responsible for the working pressure in the pipeline.

Drencher automatic fire extinguishing systems (drencher curtains) differ from sprinkler ones in that they do not have thermal locks. They are also distinguished by high water consumption and the possibility of simultaneous operation of all sprinklers. Sprinkler nozzles are various kinds: inkjet with high pressure, two-phase gas-dynamic, with liquid atomization by impact with deflectors or by interaction of jets. When designing deluge curtains, the following are taken into account: type of deluge, expected pressure, distance between sprinklers and their number, pump power, pipeline diameter, volume of liquid tanks, installation height of deluges.

Drencher curtains solve the following tasks:

localization of the fire;

dividing areas into controlled sectors and preventing the spread of fires, as well as harmful products burning outside the sector;

Cooling of technological equipment to acceptable temperatures.

Last time wide application received automatic fire extinguishing systems using water mist. The droplet size after spraying can reach 150 microns. The advantage of this technology is the more efficient use of water. In the case of extinguishing fires using conventional installations, only a third of the total volume of water is used to extinguish the fire. Fine water extinguishing technology creates a water mist that eliminates fire. This technology allows you to eliminate fires with a high degree of efficiency with rational water consumption.

1.2 Powderinstallations

The principle of operation of such devices is based on extinguishing a fire by supplying a fine powder composition to the fires. According to current regulations fire safety, all public and administrative buildings, technological premises and electrical installations, as well as storage and production premises must be equipped with automatic powder installations.

Installations do not provide a complete cessation of combustion and should not be used to extinguish fires:

Combustible materials prone to spontaneous combustion and smoldering inside the volume of the substance ( sawdust, cotton, grass flour, paper, etc.);

· chemicals and their mixtures, pyrophoric and polymeric materials prone to smoldering and burning without air access.

1.3 Gasinstallations

The purpose of gas fire extinguishing installations is to detect fires and supply a special fire extinguishing gas. They use active compositions in the form of liquefied or compressed gases.

Compressed fire extinguishing mixtures include, for example, Argonite and Inergen. All ingredients are based on natural gases, which are already present in the air, such as nitrogen, carbon dioxide, helium, argon, so their use does not harm the atmosphere. The method of extinguishing with such gas mixtures is based on the substitution of oxygen. It is known that the combustion process is supported only when the oxygen content in the air is not less than 12-15%. When liquefied or compressed gases are released, the amount of oxygen falls below the above figures, which leads to the extinction of the flame. It must be taken into account that a sharp decrease in the level of oxygen inside a room in which people are present can lead to dizziness or even fainting, therefore, when using such fire extinguishing mixtures, evacuation is usually necessary. Liquefied gases used for fire fighting purposes include: carbon dioxide, mixtures and synthesized gases based on fluorine, for example, freons, FM-200, sulfur hexafluoride, Novec 1230. Freons are divided into ozone-friendly and ozone-depleting. Some of them can be used without evacuation, while others can only be used indoors in the absence of people. Gas installations are most suitable for ensuring the safe operation of electrical equipment that is energized. Liquefied and compressed gases are used as fire extinguishing agents.

Liquefied:

freon23;

freon125;

freon218;

freon227ea;

Freon318C;

hexaphosphoric sulfur;

Inergen.

1.4 Foaminstallations

Foam fire extinguishing installations are mainly used to extinguish flammable liquids and combustible liquids in tanks, combustible substances and oil products located both inside and outside buildings. Foam APT deluge installations are used to protect local areas of buildings, electrical appliances, transformers. Sprinkler and deluge installations for water and foam fire extinguishing have a fairly close purpose and device. A feature of APT foam installations is the presence of a tank with a foaming agent and dosing devices, with separate storage of the components of the fire extinguishing agent.

The following dosing devices are used:

· Dosing pumps that supply the foaming agent to the pipeline;

· Automatic dispensers with a Venturi pipe and a diaphragm-plunger regulator (with an increase in water flow, the pressure drop in the Venturi pipe increases, the regulator provides an additional amount of foam concentrate);

ejector-type foam mixers;

· Dosing tanks using the differential pressure created by the Venturi pipe.

Another distinctive feature of foam fire extinguishing installations is the use of foam sprinklers or generators. There are a number of disadvantages inherent in all water and foam fire extinguishing systems: dependence on water supply sources; the difficulty of extinguishing premises with electrical installations; complexity of maintenance; large, and often irreparable, damage to the protected building.

1.5 Aerosolinstallations

For the first time, the use of aerosol means for extinguishing fires was described in 1819 by Shumlyansky, who used black powder, clay and water for these purposes. In 1846, Kuhn proposed boxes filled with a mixture of saltpeter, sulfur and coal (smoky powder), which he recommended to throw into a burning room and tightly close the door. Soon the use of aerosols was discontinued due to their low efficiency, especially in leaky rooms.

Volumetric aerosol fire extinguishing installations do not provide a complete cessation of combustion (fire suppression) and should not be used to extinguish:

fibrous, loose, porous and other combustible materials prone to spontaneous combustion and (or) smoldering inside the layer (volume) of the substance (sawdust, cotton, grass flour, etc.);

chemicals and their mixtures, polymeric materials prone to smoldering and burning without air access;

metal hydrides and pyrophoric substances;

metal powders (magnesium, titanium, zirconium, etc.).

It is forbidden to use the settings:

in rooms that cannot be left by people before the generators start working;

rooms with big amount people (50 people or more);

· premises of buildings and structures of III and lower degree of fire resistance according to SNiP 21-01-97 installations using fire-extinguishing aerosol generators having a temperature of more than 400 ° C outside the zone 150 mm from the outer surface of the generator.

1.6 Combinedinstallation

Automatic combined fire extinguishing installation (AUKP) - an installation that provides fire extinguishing with the help of several fire extinguishing agents.

Typically, AUCS is a combination of two individual fire extinguishing installations that have a common object of protection and an operation algorithm (for example, combinations of fire extinguishing agents: medium expansion powder-foam; low expansion powder-foam; powder-sprayed water; gas-medium expansion foam; gas-foam low expansion; gas-atomized water; gas-gas; powder-gas). The choice of a combination of fire extinguishing agents should take into account the features of fire extinguishing: the rate of fire development, the presence of heated protected surfaces, etc.

2. casesVwhichinstallationautomaticsystemsfirefightingobligatory

fire extinguishing sprinkler deluge automatic

In accordance with the current fire safety standards, the above systems must be equipped without fail:

· data centers, server rooms, data centers - data processing centers, as well as other premises intended for storage and processing of information and museum valuables;

· underground car parks of the closed type; elevated parking lots with more than one floor;

One-story buildings constructed from light metal structures with the use of combustible heaters: for public purposes - with an area of over 800 m2, for administrative purposes - with an area of over 1200 m2;

Buildings selling flammable and combustible liquids and materials, except for those selling packages up to 20 liters;

buildings with a height of more than 30 meters (except industrial buildings included in the fire hazard categories "G" and "D", as well as residential buildings);

buildings of trade enterprises (except for those engaged in trade and storage of products made from non-combustible materials): over 200 m2 - in the basement or basement floors, more than 3500 m2 - in the ground part of the building;

· all one-story exhibition halls with an area of more than 1000 m2, as well as more than two floors;

· cinema and concert halls with a capacity of more than 800 seats;

other buildings and structures in accordance with fire safety standards.

2.1 AdvantagesAndflawsautomaticfirefighting

Not all substances used for fire extinguishing are safe for the human body: some contain chlorine and bromine in their composition, which adversely affect internal organs; others dramatically lower the degree of oxygen in the air, which can cause suffocation and lead to loss of consciousness; others irritate the respiratory and visual systems of the body.

Firefighting with water is one of the most effective and safe methods for most all cases. However, this method of fighting fires requires a large amount of water needed to extinguish the fire. It is necessary to build capital engineering structures for uninterrupted water supply. In addition, water during extinguishing can cause serious material damage.

Among the advantages of gas installations, it is worth noting the following:

Extinguishing fires with their help does not lead to corrosion of equipment;

the consequences of their use are easily eliminated with the help of standard ventilation of the room;

They are not afraid of rising temperatures and do not freeze.

Along with the above advantages, the disadvantage of some gases is their rather high danger to humans. Recently, however, scientists have developed completely safe gaseous substances, for example, Novec 1230. In addition to safety for human health, the indisputable advantage of this substance is its harmlessness to the atmosphere. Novec 1230 is completely safe for the ozone layer, does not contain chlorine and bromine, its molecules completely break down under the influence of ultraviolet radiation in about five days. In addition, it is not dangerous for any property. This substance is certified, including compliance with fire safety rules and regulations, sanitary and epidemiological standards, and can be used throughout Russia. An automatic fire extinguishing system using Novec 1230 is able to quickly eliminate fires of various complexity classes.

The use of powder systems for extinguishing fires is absolutely harmless to the human body. The powder is very easy to use and costs very little. It does not harm the premises and property, but has a short shelf life.

Conclusion

The purpose of using automatic fire extinguishing installations is to localize and extinguish fires, save the lives of people and animals, as well as real and movable property. The use of such tools is the most effective method fire fighting. Unlike hand tools fire fighting and alarm systems, they create everything the necessary conditions for effective and prompt localization of fires with minimal risk to health and life.

Bibliographiclist

1. Federal Law No. 123 of July 22, 2008 "Technical regulation on fire safety requirements"

2. Smirnov N.V., Tsarichenko S.G., Zdor V.L. and others. “Regulatory and technical documentation on the design, installation and operation of fire extinguishing installations, fire alarms and smoke removal systems” M., 2004;

3. Baratae A.N. "Fire and explosion hazard of substances and materials and means of extinguishing them" M., 2003.

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Main aspects of gas fire extinguishing

Gas fire extinguishing is separate view extinguishing fires, in which special gaseous substances are used. This method is optimal, since when the protective line is triggered, all equipment in the room is preserved and not affected. special means extinguishing fires. This subsystem is more expensive than the others. In practice, this type of protection is installed in hermetically sealed rooms or places where valuables are stored. The use of gas makes it possible to extinguish the fire effectively, since the entire perimeter of the object is filled with it. The gas enters hard-to-reach places where foam or powder cannot enter.

On the video - a presentation of the system gas fire extinguishing:

The advantages of using a gas fire extinguishing system are:

Absence negative influence to the ozone layer
When using gas, there is no greenhouse effect;
Such special equipment has a long shelf life;
When contact with fire occurs, poisonous or toxic compounds are not formed;
Short-term fire extinguishing;
There are no significant differences in atmospheric pressure;
The gas fire extinguishing system allows you to extinguish the fire in several rooms at the same time.

The use of such fire fighting equipment may have a modular and centralized type of control. Large financial costs for the installation of equipment is not required. An important aspect is the timely filling of the modules with an extinguishing agent after the automatic operation of the system. The use of gas to extinguish a fire is classified into three classes based on the object that ignited:

Class "A" - solid combustible substances and materials (plastic, fabric, paper, wood, etc.);
Class "B" - flammable fuels and lubricants (oil, petroleum products, gasoline, varnishes, paints, etc.);
Class "C" - combustible gases.

Gas fire extinguishing according to current safety standards may include the following fire extinguishing agents:

Carbon dioxide (CO2);
Freon (CF3H), 125 (C2F5H), 218 (C3F8), 227 (C3F7H), 318 (C4F8H);
Sulfur hexafluoride (SF6);
Argon (Ar);
Nitrogen;
Inergen;
Argonite;
gas mixtures.

Complex composition of gas fire extinguishing systems

Gas extinguishing systems consist of the following components:

Special modules;
Distribution devices;
Nozzles;
pipelines.

Special modules (tanks) are designed for gas storage. When the device is automatically triggered, the gas is discharged through the pipelines. The modules are made in the form of cylinders. Cylinders are equipped with a locking-starting mechanism. They can be made from various materials. Depending on the functional features of the system as a whole, the volume and pressure can also be varied. As practice shows, high-strength steel is most often used for the manufacture of cylinders. WITH inside containers are covered with a polymeric substance. This treatment performs an anti-corrosion function.

The locking and starting mechanism works with the help of an electromagnet or a squib. With a large area of \u200b\u200bthe room, gas fire extinguishing includes several installations, and for small rooms, one is enough. Distribution devices are installed to move the extinguishing agent into the pipeline. This device is presented in the form of a triple valve. The design is equipped with a shut-off valve and a mechanism that allows you to lift the substance and direct it into the pipeline.

The gas distribution mechanism can be controlled manually or remotely.

Nozzles allow you to spray the extinguishing agent. They are usually installed on pipelines. Pressure is created in the nozzle, under which gas escapes. The set pressure allows you to determine the spray range. Spraying must be carried out from all sides: at an angle of 360º. The pipelines transport the gas to the nozzles. Gas fire extinguishing is designed according to various technical parameters. The cross section, volume and length of pipelines are determined individually for each room, so that the gas supply is efficient. In places with a high fire hazard coefficient, steel pipelines are used.

Scope of the system

Gas fire extinguishing is intended for use in rooms where valuables or expensive equipment are located. For example, in server rooms where electronic equipment is installed, such a system should be installed. Using water, powder, or foam to extinguish a fire can result in equipment failure. This type of fire extinguishing is used in places where relics, historical cultural monuments are stored: in museums, libraries.

Along with the use of gas to extinguish a fire, isolation technology can be used. In the presence of special installations, in the event of a fire, oxygen access is eliminated. The oxygen level is reduced to a minimum at which it is impossible to maintain the combustion process. In crowded places (train stations, airports), special compositions are used for gas systems. In such cases, oxygen access cannot be limited. Each fire extinguishing system is designed individually, taking into account many factors.

The video shows how the gas fire extinguishing of the production room is carried out:

Design of the installation of a gas fire extinguishing complex

When installing a gas fire extinguishing line at the facility, it is necessary to draw up a detailed design, which includes the following sections:

Explanatory note;
Technological part;
Electrical part;
Description of the specifics of equipment and materials;
Estimate (its availability depends on the requirements of the customer).

The explanatory note must contain general provisions, purpose, brief description protected object. IN general provisions the basis for the design of the system and the name of the object are indicated. Be sure to list the regulatory documents that were used in the preparation project documentation. Next, the model of the gas installation, its purpose and functionality are indicated. The characteristics of the premises contain an indication of the area of the protected object. The following indicators are noted:

Atmosphere pressure;
Air temperature;
Humidity;
Technical characteristics of ventilation;
Features of structures;
Zones are classified.

The technological part of the documentation contains a description of the integrated fire extinguishing installation. All constituent elements are described: module type, fire safety certificates, nozzles, nozzles, pipelines, etc. The same subsection presents calculation formulas that contain information about the concentration of the extinguishing agent in a particular room. One of the main formulas is the calculation of the time for the evacuation of all people from the premises. The exact time when the equipment stops working is indicated. On average, this time is 10 seconds. A delay in the operation of an automatic gas extinguishing system is undesirable, since it is intended to eliminate the source of fire at an early stage.

When performing calculations, it is imperative to take into account structures that are constantly open.

The electrical section of the documentation contains the following provisions:

Principles for the selection of devices announcing the occurrence of a fire;
Their name, type, certificate number;
Description of receiving, control and control mechanisms, their serial numbers and certificate numbers;
The functionality of the device is briefly described;
The principle of operation of the equipment (mandatory includes four subsections, including the “Automatics on and off” modes, remote and modular start, power supply);
Elemental composition and their placement;
Installation location and technical requirements to him;
Marking of wires, cables, the order of their laying;
Composition of persons (professional and qualification) who carry out the installation and maintenance of equipment;
Description of the required qualification level;
The number of service personnel;
List of labor protection measures;
Safety briefing;
Requirements for persons providing maintenance of mechanisms;
Algorithm of actions in case of system operation and fire.

Design, installation and service of fire extinguishing systems are carried out by specialized companies.

24.12.2014, 09:59

S. Sinelnikov
head of the design department of Technos-M + LLC

Recently, in fire safety systems of small objects to be protected by automatic fire extinguishing systems, automatic gas fire extinguishing installations are becoming more common.

Their advantage lies in fire-extinguishing compositions that are relatively safe for humans, the complete absence of damage to the protected object when the system is triggered, repeated use of equipment and extinguishing a fire in hard-to-reach places.

When designing installations, questions most often arise regarding the choice of fire extinguishing gases and the hydraulic calculation of installations.

In this article we will try to reveal some aspects of the problem of choosing a fire extinguishing gas.

All gas fire extinguishing compositions most commonly used in modern gas fire extinguishing installations can be divided into three main groups. These are substances of the freon series, carbon dioxide - commonly known as carbon dioxide (CO2) - and inert gases and mixtures thereof.

In accordance with NPB 88-2001 *, all these gaseous fire extinguishing agents are used in fire extinguishing installations for extinguishing fires of class A, B, C, according to GOST 27331, and electrical equipment with a voltage not exceeding that specified in technical documentation on the applied GOTV.

Gas fire extinguishers are mainly used for volumetric fire extinguishing in initial stage fire according to GOST 12.1.004-91. GOTVs are also used for phlegmatization of an explosive environment in the petrochemical, chemical and other industries.

fumes are non-conductive, easily evaporate, do not leave marks on the equipment of the protected object, in addition, an important advantage of fumes is their

suitability for extinguishing expensive electrical installations under tension.

It is forbidden to use GOTV for extinguishing:

a) fibrous, loose and porous materials capable of spontaneous combustion with subsequent smoldering of a layer inside the volume of the substance (sawdust, rags in bales, cotton, grass flour, etc.);

b) chemicals and their mixtures, polymeric materials prone to smoldering and burning without air access (nitrocellulose, gunpowder, etc.);

c) reactive metals (sodium, potassium, magnesium, titanium, zirconium, uranium, plutonium, etc.);

d) chemicals capable of undergoing autermic decomposition (organic peroxides and hydrazine);

e) metal hydrides;

e) pyrophoric materials ( white phosphorus, organometallic compounds);

g) oxidizers (nitrogen oxides, fluorine). It is forbidden to extinguish class C fires if it is possible to release or enter combustible gases into the protected volume, followed by the formation of an explosive atmosphere.

In the case of using GFEA for fire protection of electrical installations, the dielectric properties of gases should be taken into account: dielectric constant, electrical conductivity, electrical strength.

As a rule, the maximum voltage at which it is possible to carry out extinguishing without turning off electrical installations with all GFFS is no more than 1 kV. Only CO2 can be used to extinguish electrical installations with voltages up to 10 kV premium- according to GOST 8050.

Depending on the extinguishing mechanism, gas fire extinguishing compositions are divided into two qualification groups:

1) inert diluents that reduce the oxygen content in the combustion zone and form an inert environment in it (inert gases - carbon dioxide, nitrogen, helium and argon (types 211451, 211412, 027141, 211481);

2) inhibitors that slow down the combustion process (halocarbons and their mixtures with inert gases - freons).

Depending on the state of aggregation, gas fire extinguishing compositions in storage conditions are divided into two classification groups: gaseous and liquid (liquids and / or liquefied gases and solutions of gases in liquids).

The main criteria for choosing a gas extinguishing agent are:

■ Safety of people.

■ Technical economic indicators.

■ Preservation of equipment and materials.

■ Application restriction.

■ Environmental impact.

■ Possibility of removal of GOTV after application.

It is preferable to use gases that:

■ have acceptable toxicity in the fire extinguishing concentrations used (suitable for breathing and allow personnel to be evacuated even when gas is supplied);

■ thermally stable (form a minimum amount of thermal decomposition products that are corrosive, irritating to the mucous membrane and poisonous when inhaled);

■ most effective in fire extinguishing (protect the maximum volume when supplied from the module, which is filled with gas to the maximum value);

■ economical (provide minimum specific financial costs);

■ environmentally friendly (do not have a destructive effect on the Earth's ozone layer and do not contribute to the greenhouse effect);

■ provide versatile methods for module filling, storage and transportation, and refilling. The most effective in extinguishing a fire are chemical gases-freons. The physico-chemical process of their action is based on two factors: chemical inhibition of the oxidation reaction process and a decrease in the concentration of the oxidizing agent (oxygen) in the oxidation zone.

Freon-125 has undoubted advantages. According to NPB 882001*, the normative fire extinguishing concentration of freon-125 for class A2 fires is 9.8% vol. This concentration of freon-125 can be increased to 11.5% vol., while the atmosphere is breathable for 5 minutes.

If GOTV is ranked by toxicity in case of a massive leak, then compressed gases are the least dangerous, because carbon dioxide protects a person from hypoxia.

The freons used in the systems (according to NPB 88-2001 *) are of low toxicity and do not show a pronounced picture of intoxication. In terms of toxicokinetics, freons are similar to inert gases. Only with prolonged inhalation exposure to low concentrations, freons can have an adverse effect on the cardiovascular, central nervous system, lungs. With inhalation exposure to high concentrations of freons, oxygen starvation develops.

Below is a table with temporary values of a person's safe stay in the environment of the most commonly used freon brands in our country at various concentrations (Table 1).

Concentration, % (vol.)	10,0 \| 10,5 \| 11,0	12,0 12,5 13,0
Safe exposure time, min.
Freon 125HP
Freon 227ea

The use of freons in fire fighting is practically safe, because. fire-extinguishing concentrations for freons are an order of magnitude less than lethal concentrations with exposure duration up to 4 hours. Approximately 5% of the mass of freon supplied to extinguish a fire is subjected to thermal decomposition, therefore the toxicity of the environment formed when extinguishing a fire with freons will be much lower than the toxicity of pyrolysis and decomposition products.

Freon-125 is ozone-safe. In addition, it has maximum thermal stability compared to other freons, the thermal decomposition temperature of its molecules is more than 900 ° C. The high thermal stability of freon-125 allows it to be used to extinguish fires of smoldering materials, because at the smoldering temperature (usually about 450 ° C), thermal decomposition practically does not occur.

Freon-227ea is no less safe than freon-125. But their economic indicators as part of a fire extinguishing installation are inferior to freon-125, and the efficiency (protected volume from a similar module) differs slightly. It is inferior to freon-125 in terms of thermal stability.

The specific costs of CO2 and freon-227ea practically coincide. CO2 is thermally stable in firefighting. But the effectiveness of CO2 is low - a similar module with freon-125 protects the volume by 83% more than the CO2 module. The fire extinguishing concentration of compressed gases is higher than that of freons, therefore, 25-30% more gas is required, and, consequently, the number of containers for storing gaseous fire extinguishing agents increases by a third.

Effective fire extinguishing is achieved at a CO2 concentration of more than 30% vol., but such an atmosphere is unsuitable for breathing.

Carbon dioxide at concentrations over 5% (92 g/m3) bad influence on human health, the volume fraction of oxygen in the air decreases, which can cause the phenomenon of oxygen deficiency and suffocation. Liquid carbon dioxide, when the pressure drops to atmospheric pressure, turns into gas and snow at a temperature of -78.5 ° C, which cause frostbite of the skin and damage to the mucous membrane of the eyes.

In addition, when using coal acid automatic fire extinguishing installations ambient air temperature working area should not exceed +60°C.

In addition to freons and CO2, inert gases (nitrogen, argon) and their mixtures are used in gas fire extinguishing installations. The absolute environmental friendliness and safety for humans of these gases are the undoubted advantages of their use in AUGPT. However, the high fire-extinguishing concentration and the associated larger (compared to freons) amount of required gas and, accordingly, a larger number of modules for its storage, make such installations more bulky and expensive. In addition, the use of inert gases and their mixtures in AUGPT is associated with the use of higher pressure in the modules, which makes them less safe during transportation and operation.

IN last years modern fire-extinguishing agents of a new generation began to appear on the domestic market.

These special formulations are predominantly produced abroad and have, as a rule, a high cost. However, their low fire-extinguishing concentration, environmental friendliness and the ability to use low-pressure modules make their use attractive and promise good prospects for the use of such fumes in the future.

Based on all of the above, we can say that the most effective and currently available fire extinguishing agents are freons. Relatively high price of freons is compensated by the cost of the installation itself, installation of the system and its maintenance. A particularly important quality of freons used in fire extinguishing systems (in accordance with NPB 88-2001 *) is their minimally harmful effect on humans.

Tab. 2. Summary table of characteristics of the most commonly used GOTV in the territory of the Russian Federation

CHARACTERISTIC	GAS EXTINGUISHING AGENT
Name GOTV	carbon dioxide		Freon 125	Freon 218	Freon 227ea	Freon 318C	Sulfur hexafluoride
Name variations	Carbon dioxide	TFM18, FE-13			FM200, IGMER-2
Chemical formula										N2 - 52%, Ag - 40% CO2 - 8%
		TU 2412-312 05808008	TU 2412-043 00480689	TU 6-021259-89	TU 2412-0012318479399	TU 6-021220-81
Fire classes	AND ALL UP TO 10000 V
Fire extinguishing efficiency (fire class A2 n-heptane)
Minimum volumetric fire extinguishing concentration (NPB 51-96*)
Relative permittivity (N2 = 1.0)
Module fill factor
Aggregate state in AUPT modules	Liquefied gas	Liquefied gas	Liquefied gas	Liquefied gas	Liquefied gas	Liquefied gas	Liquefied gas	compressed gas	compressed gas	compressed gas
Mass control of GOTV	Weighing device	Weighing device	pressure gauge	pressure gauge	pressure gauge	pressure gauge	pressure gauge	pressure gauge	pressure gauge	pressure gauge
Pipe wiring	No limits	No limits	Taking into account the stratification	No limits	Taking into account the stratification	Taking into account the stratification	No restrictions	No limits	No limits	No limits
The need for boost
Toxicity (NOAEL, LOAEL)					9,0%, > 10,5%
Interaction with fire load	Strong cooling		>500-550 °С	> 600 °C highly toxic				Absent	Absent	Absent
Calculation methods	MO, LPG NFPA12		MO, ZALP, NFPA 2001		MO, ZALP, NFPA 2001
Availability of certificates					FM, UL, LPS, SNPP
Warranty period of storage
Production in Russia

Gas fire extinguishing installations are specific, expensive and quite difficult to design and install. Today, there are many companies that offer various settings gas fire extinguishing. Since there is little information in open sources on gas fire extinguishing, many companies mislead the customer, exaggerating the merits or hiding the shortcomings of certain gas fire extinguishing installations.

Gas fire extinguishing has more than a century of history. The use of carbon dioxide (CO2) to extinguish fires was first started at the end of the 19th century in countries Western Europe and USA, but wide use this fire extinguishing method was received only after the Second World War, when freons began to be used as the main component of the GOS.

Basics and classification

At the moment, the regulatory documents in force in the Russian Federation allow the use of gas fire extinguishing compositions based on carbon dioxide, nitrogen, inergen argon, sulfur hexafluoride, as well as freon 227, freon 23, freon 125 and freon 218. According to the principle of operation, all GOS can be divided into two groups:

Deoxidants (oxygen displacers) are substances that create a concentrated cloud around the combustion source, preventing the flow of oxygen and thus “suffocating” the ignition source. This group includes GOS based on carbon dioxide, nitrogen, argon and inergen.

Inhibitors (combustion suppressors) are substances that enter into the atmosphere with burning substances. chemical reactions that take energy from the combustion process.

According to the method of storage, fire extinguishing gas mixtures are divided into compressed and liquefied.

The scope of gas fire extinguishing installations covers industries in which extinguishing with water or foam is undesirable, but contact of equipment or stored supplies with chemically aggressive powder mixtures is also undesirable - equipment rooms, server rooms, computer centers, ships and aircraft, archives, libraries, museums, art galleries.

Most of the substances used for the production of HOS are not toxic, however, the use of gas fire extinguishing systems creates an indoor environment unsuitable for life (this is especially true for HOS from the group of deoxidants). Therefore, gas fire extinguishing systems pose a serious danger to human life. So on November 8, 2008, during sea trials of the Nerpa nuclear submarine, an unauthorized operation of the gas fire extinguishing system led to the death of more than twenty members of the submarine's crew.

In accordance with regulations, all automatic fire extinguishing systems with GOS as a working substance must necessarily allow the possibility of delaying the supply of the mixture until the complete evacuation of personnel. Premises in which automatic gas fire extinguishing is used are equipped with GAS! DO NOT ENTER! and "GAS! LEAVE!" at the entrance to the room and exit from it, respectively.

Advantages and disadvantages of gas fire extinguishing

Fire extinguishing with the help of GOS has become widespread due to a number of advantages, including:

fire extinguishing with the help of GOS is carried out throughout the entire volume of the premises;
fire extinguishing gas mixtures are non-toxic, chemically inert; when heated and in contact with burning surfaces, they do not decompose into toxic and aggressive fractions;
gas fire extinguishing practically does not harm equipment and material values;
after the end of the extinguishing, the GOS are easily removed from the room by simple ventilation;
the use of GOS has high speed fire extinguishing.

However, gas fire extinguishing also has some disadvantages:

extinguishing a fire with gas requires sealing the room
gas fire extinguishing is ineffective in large rooms or in open space.
the storage of loaded gas modules and the maintenance of the fire suppression system are fraught with difficulties associated with the storage of substances under pressure
gas fire extinguishing installations are temperature sensitive
GOS are unsuitable for extinguishing the fire of metals, as well as substances that can burn without oxygen.

Fire extinguishing installations with the help of GOS

According to the degree of mobility, gas fire extinguishing installations can be divided into three groups:

Mobile gas fire extinguishing installations - fire extinguishing installations mounted on a wheeled or tracked chassis, towed or self-propelled (gas fire extinguishing installation "Shturm").

Portable primary extinguishing equipment - fire extinguishers and fire extinguishing batteries.

Stationary installations - permanently mounted fire extinguishing installations with the help of GOS, automatic and triggered by a command from the remote control.

In non-residential premises, in warehouses and storage facilities, at enterprises associated with the production and storage of combustible and explosive substances, automatic gas fire extinguishing systems are widely used.

Scheme of automatic gas fire extinguishing system

Since fire extinguishing with gas is highly dangerous for the personnel of the enterprise, in the case of installing an automatic fire extinguishing system with the help of GOS at enterprises with a large number employees, the integration of the system automation with the access control and management system (ACS) is required. Besides automatic system the fire extinguishing system should, at the signal of fire detectors, carry out maximum sealing of the room in which the extinguishing takes place - turn off the ventilation, as well as close automatic doors and lower protective shutters, if any.

Automatic gas fire extinguishing systems are classified:

By the volume of extinguishing - extinguishing of the full volume (the entire volume of the room is filled with gas) and local (gas is supplied directly to the source of ignition).

By centralizing the supply of fire extinguishing mixture - centralized (gas is supplied from the central tank) and modular.

According to the method of initiating the extinguishing process - with electric, mechanical, pneumatic, hydraulic descent or a combination of them.

Equipping the facility with a gas fire extinguishing system

The initial calculation and planning of the installation of a gas fire extinguishing system begins with the selection of system parameters depending on the specifics of a particular facility. Great importance It has right choice extinguishing agent.

Carbon dioxide (carbon dioxide) is one of the most inexpensive options GOS fire extinguishing. Refers to fire-extinguishing substances-dioxidants, in addition, it has a cooling effect. Stored in a liquefied state, requires weight control of leakage of the substance. Mixtures based on carbon dioxide are universal, the limitation for use is fires with ignition of alkali metals.

Gas cylinders

Freon 23 is also stored in liquid form. Due to its high self-pressure, it does not require the use of propellant gases. It is allowed to be used for extinguishing rooms in which people can stay. Environmentally friendly.

Nitrogen is an inert gas and is also used in fire extinguishing systems. It has a low cost, however, due to storage in a compressed form, nitrogen-filled modules are explosive. If the nitrogen gas fire extinguishing module does not work, it must be plentifully irrigated with water from the shelter.

Steam fire extinguishing installations are of limited use. They are used in facilities that generate steam for their operation, such as power plants, ships with steam turbine engines, etc.

In addition, before designing, it is necessary to choose the type of gas fire extinguishing installation - centralized or modular. The choice depends on the size of the object, its architecture, number of storeys and the number of separate rooms. Installation of a fire extinguishing installation of a centralized type is advisable to protect three or more rooms within one facility, the distance between which does not exceed 100m.

At the same time, it should be taken into account that centralized systems are subject to a large number of requirements of the regulatory NPB 88-2001 - the main normative document regulating the design, calculation and installation of fire-fighting installations. Gas modules according to their design, fire extinguishers are divided into unitary modules - they include in their design one container with a compressed or liquefied extinguishing gas mixture and a propellant gas; and batteries - several cylinders connected by a manifold. Based on the plan, a gas fire extinguishing project is being developed.

Designing a fire-fighting system using GOS

It is desirable that the entire range of works related to equipping the facility with a fire system (design, calculation, installation, commissioning, maintenance) is carried out by one contractor. The design and calculation of the gas fire extinguishing system is carried out by a representative of the installer in accordance with NPB 88-2001 and GOST R 50968. The installation parameters (quantity and type of fire extinguishing agent, centralization, number of modules, etc.) are calculated based on the following parameters:

number of rooms, their volume, availability suspended ceilings, false wall.
area of permanently open openings.
temperature, barometric and hygrometric (air humidity) conditions at the facility.
availability and mode of operation of personnel (ways and time of personnel evacuation in case of fire).

When calculating the estimate for the installation of fire extinguishing equipment, some specific aspects should be taken into account. For example, the cost of one kilogram of fire extinguishing gas mixture is higher when using modules with compressed gas, since each such module contains a smaller mass of substance than a module with compressed gas. liquefied gas, therefore, the latter will be required less.

Installation and maintenance cost centralized system as a rule, extinguishing is less, however, if the object has several fairly remote premises, the savings are “eaten up” by the cost of pipelines.

Installation and maintenance of a gas fire extinguishing station

Before starting installation work on the assembly of a gas fire extinguishing installation, it is necessary to make sure that there are certificates for the equipment subject to mandatory certification and to check the availability of a license to work with gas, pneumatic and hydraulic equipment from the installer.

A room equipped with a gas fire extinguishing station must be equipped with exhaust ventilation to remove air. The air removal rate is three for freons and six for deoxidants.

The manufacturer carries out installation of fire extinguishing modules or centralized balloon tanks, main and distribution pipelines and starting systems. The modular or centralized pipeline part of the gas extinguishing station is integrated into a single automated control and monitoring system.

Pipelines and elements of the automated control system should not violate appearance and functionality of the premises. Upon completion of installation and commissioning, an act of work performed is issued, and an acceptance certificate is issued to which test reports and technical passports of the equipment used are attached. A maintenance contract is signed.

Equipment performance tests are repeated at least once every five years. Maintenance gas extinguishing systems includes:

regular performance tests of the elements of the gas extinguishing station;
routine maintenance and current repair of equipment;
weight tests of modules for the absence of leakage of GOS.

Despite certain difficulties associated with installation and use, gas systems fire extinguishers have a number of undoubted advantages and high efficiency in its field of application.

Currently, when extinguishing a fire in rooms with electrical equipment, museums, archives, libraries and some other objects, gas fire extinguishing is used as the most effective, environmentally friendly way to fight fire.

Compressed gases (nitrogen or argon) and freons are used as a fire extinguishing agent in gas fire extinguishing installations.

Advantages of gas fire extinguishing

Gas fire extinguishing has a number of undeniable advantages over other types of fire extinguishing - aerosol, water, foam and powder. The main ones are:

lightning speed of extinguishing fires;
the penetration of gases into hard-to-reach places of the entire room;
the possibility of lightning-fast elimination of consequences (with the help of ventilation);
environmental safety for humans and lack of negative impact on the environment;
no impact on property and material values.

In connection with such features, gas fire extinguishing is used in crowded places (due to absolute harmlessness to the human body), museums, archives, libraries, rooms with electrical equipment, where it is important to preserve material values. They can operate over a wide temperature range.

Components of gas fire extinguishing installations

Main constituent elements automatic installation gas fire extinguishing:

container with fire extinguishing agent (cylinder or module);
pipeline system (with nozzles);
receiving and control device;
Control block;
detectors.

They are systems with a well-coordinated sequential algorithm of action; when designing them, specialists take into account a number of factors, including the properties of gases, the response of gas storage tanks to temperature changes.

In most cases, modular gas fire extinguishing installations are used in production and various facilities. Module - a cylinder for the manufacture of which steel is used. A shut-off and starting device is placed on it - a valve to which a signal is received from the detector, as a result of which the ZPU is activated. After use, the cylinder can be refilled with gas.

The mechanism of operation of the gas fire extinguishing installation is to reduce the amount of oxygen in the room where the fire occurs by supplying a fire extinguishing agent - an inert gas, carbon dioxide or freon.

Argon, nitrogen, argonite and inergen are used as inert gases in the installations, which do not adversely affect people and can be used to extinguish electrical equipment. Carbon dioxide plants use carbon dioxide.

How is a fire extinguished using gases? general principle It consists in the fact that, under high pressure, non-combustible gases enter the source of ignition, which significantly reduce the concentration of oxygen in the air, inhibiting the combustion process.

Sensors located in the room provide information about the beginning of a fire to the control panel.
After informing about the fire that has begun, ventilation is blocked.
Through pipelines using sprayers, the gas escapes to the outside, while with an increased concentration it is possible to extinguish the fire faster.

The process of gas fire extinguishing does not exceed 60 seconds, while the gas is evenly distributed throughout the room. After working out the system to eliminate the consequences of using gas, it is enough to ventilate the room.

The principle of operation is quite simple, and the complex itself allows you to cope with a fire in a matter of seconds, without harming property and people's lives.

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